While the off-engine manifold support system of the present invention may have other uses, as will be developed further hereinafter, it lends itself particularly well to its application as a support system for steam and gaseous fuel manifolds of marine and industrial gas turbine engines, and will be so described for purposes of an exemplary showing.
It is well established in the prior art that the introduction of steam into the flow path of a gas turbine engine will increase engine performance and reduce emissions. Steam injection increases the mass flow and therefore increases the power output. Furthermore, steam injection just ahead of the combustion reaction zone reduces the amount of oxides of nitrogen generated in the combustion process. Steam injection is particularly applicable to marine and industrial gas turbine engines, which are often located in environments where steam is readily available. Furthermore, the weight of the water and steam generating equipment is not the concern it would be with aircraft engines. According to prior art practice, annular steam and gaseous fuel manifolds are provided, surrounding and substantially coaxial with the gas turbine engine, frequently near the combustor stage thereof. Support for these manifolds has traditionally taken the form of links or braces extending from the engine flanges or fuel nozzle pads. Secondary support has been provided by utilizing rigid supply lines between the manifold outlets and the fuel nozzles.
This prior art support approach for the steam and gaseous fuel manifolds has not been entirely satisfactory. Dynamic and thermal stresses have been a problem and field failures have occured in several areas, manifested by damaged fuel nozzles, broken links, cracks in engine casings, and the like.
The problems were intensified in instances where the gas turbine engine did not have flanges conveniently located for the supporting links. In some instances the links simply would have to be too long to afford adequate support. In other instances, there simply was no flange within reach of a supporting link.
Furthermore, analyses have revealed that the on-engine approach frequently demonstrates resonances in the engine operating range, which could not be moved by fine-tuning the system. Where flanges were so located that extra long links or brackets were required to support the manifolds, the already unacceptable stress levels were compounded.
The present invention is based upon the discovery that these disadvantages can be avoided utilizing an off-engine support approach. The manifolds are each supported by a pair of stanchions mounted on the foundation structure supporting the engine itself. Each stanchion is provided with bracket assemblies which engage its respective manifold, permitting position adjustment thereof. The outlets of the manifolds are connected to their respective nozzles by flexible metal hoses which are not relied upon for manifold support.
As a consequence of this off-engine support, it has been found that the manifolds are dynamically and thermally isolated from the gas turbine engine. The use of the flexible metal hoses results in very low stresses in the fuel nozzles. The approach enables the provision of more precisely positioned customer interfaces, and the off-engine support system of the present invention is characterized by greater simplicity, less maintenance and lower cost than existing support systems.